Re: [patch v2 2/3] mm, thp: really limit transparent hugepage allocation to local node

From: Vlastimil Babka
Date: Mon Mar 02 2015 - 08:47:30 EST


On 02/27/2015 11:17 PM, David Rientjes wrote:
Commit 077fcf116c8c ("mm/thp: allocate transparent hugepages on local
node") restructured alloc_hugepage_vma() with the intent of only
allocating transparent hugepages locally when there was not an effective
interleave mempolicy.

alloc_pages_exact_node() does not limit the allocation to the single
node, however, but rather prefers it. This is because __GFP_THISNODE is
not set which would cause the node-local nodemask to be passed. Without
it, only a nodemask that prefers the local node is passed.

Fix this by passing __GFP_THISNODE and falling back to small pages when
the allocation fails.

Commit 9f1b868a13ac ("mm: thp: khugepaged: add policy for finding target
node") suffers from a similar problem for khugepaged, which is also
fixed.

Fixes: 077fcf116c8c ("mm/thp: allocate transparent hugepages on local node")
Fixes: 9f1b868a13ac ("mm: thp: khugepaged: add policy for finding target node")
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>

Acked-by: Vlastimil Babka <vbabka@xxxxxxx>

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